1. Field of the Invention
The invention relates to a lubrication control device for a transmission.
2. Description of Related Art
As an example of a device for adjusting the temperature of oil for a transmission, Japanese Patent Application Publication No. 2002-266993 (JP 2002-266993 A) discloses a hydraulic oil cooling device for an automatic transmission for a vehicle. The hydraulic oil cooling device is provided with a water-cooled oil cooler and an air-cooled oil cooler which are connected in series to each other and cools hydraulic oil that circulates through an oil pump for the automatic transmission for a vehicle, an oil pressure control circuit, and a lubrication circuit of a transmission mechanism. A cooler bypass valve and a bypass valve are disposed in the hydraulic oil cooling device for an automatic transmission for a vehicle. The cooler bypass valve allows the hydraulic oil to bypass the water-cooled oil cooler and the air-cooled oil cooler and circulate through the oil pump, the oil pressure control circuit, and the lubrication circuit only in a case where the temperature of the hydraulic oil does not exceed a predetermined value and a hydraulic oil line pressure generated in the oil pump is not exceeded by a predetermined value. The bypass valve allows the hydraulic oil to bypass only the air-cooled oil cooler and circulate through the oil pump, the oil pressure control circuit, and the lubrication circuit in a case where the detected temperature of the hydraulic oil does not reach a required value.
According to JP 2002-266993 A, the hydraulic oil is warmed by engine coolant in the water-cooled oil cooler in a case where the hydraulic oil temperature is low. In this case, a rise in the temperature of the hydraulic oil is promoted. The hydraulic oil cooling device for an automatic transmission for a vehicle according to JP 2002-266993 A is configured to allow an oil passage passing through the oil cooler and an oil passage bypassing the oil cooler to be merged with each other on the further upstream side than the lubrication circuit.